The installation of wall-to-wall carpeting typically involves joining two or more pieces of carpet together to form an expanse of carpeting sufficiently large to carpet an entire area. Typically, carpet is then rolled out in the room, usually over some padding, cut, fitted, seamed, and stretched. This process is intended to remove any wrinkles or creases in the carpeting, resulting in a flat, safe and visually appealing carpet installation.
In the past, seams were created by sewing two abutting edges of adjoining carpet pieces together, as described in, e.g., U.S. Pat. Nos. 3,440,981, 3,457,884, and 3,499,402, to produce seams of high strength which are able to withstand stretching during installation. However, this method is very labor intensive, and therefore very costly and time-consuming to produce. If done too quickly, or by a person not sufficiently skilled, the joined edges could be improperly aligned or carpet pile caught by the thread, making the seam visible and unsightly. This has proven inimical to the efficient and economical installation of seamed carpeting.
In recent years, carpet installers have turned to seaming using hot melt adhesive seaming tape. This method avoids the significant time and effort burdens imposed by sewing and enables seaming to be conducted by relatively unskilled workers. In this process, a strip of tape having a layer of hot melt adhesive is centered under the seam with the layer of hot melt adhesive facing up. A carpet seaming iron, or other suitable implement, is used to melt the hot melt adhesive, and the carpet backing is pushed into the molten hot melt adhesive with the two edges abutting. The adhesive quickly sets, forming a permanent seam. This method is generally disclosed by, e.g., U.S. Pat. No. 3,972,768, 4,097,445, and 4,416,713.
Temperature control at the base of the carpet seaming iron is very important: if the iron is too cool, the hot melt adhesive will take too long to melt; if the iron is too hot, the adhesive will melt too quickly and the operator will have to work faster than is prudent. Conventional carpet seaming irons are typically produced with solid base plates, which resist quick temperature changes. While this is a useful means of maintaining the correct temperature, it can delay necessary temperature adjustment when the temperature is not correct. A solid base plate also adds substantially to the weight of the iron.
In addition, the base plate and housing of the carpet seaming iron become sufficiently hot at typical operating temperatures to deform or burn the overlying pieces of carpet to be seamed. To prevent damage to the carpet (and injury to the operator), conventional carpet seaming irons are provided with heat shields. However, even with a heat shield, heat can build up inside the housing and cause the handle and heat shield to become quite hot, causing discomfort or even injury to the operator and degradation to the carpet backing. This problem has been addressed in part by U.S. Pat. No. 5,333,401; however the '401 patent requires a complicated arrangement with a two-element sole plate and a pair of spaced apart sheets forming a channel separating the handle from the sole plate through which air can flow from the front of the iron to the rear. These additional elements are not believed to produce a significant decrease in the temperature of the heat shield, but do increase the weight of the iron which will unnecessarily fatigue the operator.
Accordingly, the need exists for a light-weight carpet seaming iron with improved temperature control, which reaches the desired temperature quickly, retains that temperature by automatic adjustment, and includes means for keeping the temperature of the handle and heat shield at a level which is safe for the carpeting and not uncomfortable for the operator.